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Don't love the network graph illustrating the spread of a virus. It's deceptive and is counter to the purpose of explaining exponential growth. If the people
by JackFr 12y ago
Don't love the network graph illustrating the spread of a virus.
It's deceptive and is counter to the purpose of explaining exponential growth. If the people infected are represented by relatively uniform points on a plane, and infection is shown as an ever expanding circle, the growth is geometric, not exponential. I understand that the exponential growth could be captured by the acceleration of the radius, but that is not intuitive.
- tedsanders 12y agoActually it shows polynomial growth, not geometric growth. Polynomial growth is of the form t^n whereas geometric/exponential growth is of the form n^t. (The only real difference between geometric and exponential growth is that geometric connotes discrete growth steps; otherwise they are the same.) In any case, I totally agree with your point. The virus graph is quite misleading because it shows a growing circle. The plot beside the graph doesn't even look like exponential growth!
- JackFr 12y agoYikes! I've been using "geometric growth" to mean "polynomial growth" my whole life.
- sopooneo 12y agoDarn it, me too. I always thought geometric was a special case of polynomial where you only have a ax^2 term. I figured this was a reference to the fact that geometry is usually done in the plane, and linear increase corresponds to square increase in area. I think I may have even pedantically "corrected" someone on this at some point. Awesome.